Screw-gage and the like.



PATENTED FEB. 5, 1907.

P. B. FISCHER.

SCREW GAGE AND THE LIKE.

APPLICATION FILED 00T.l6, 1903.

Z SHEETS-SHEET 1.

No. 843,265. PATENTBD FEB. 5, 1907. F. B. FISCHER.

SCREW GAGE AND THE LIKE.

APPLICATION FILED 00T.16, 1903.

2 SHEETS-SHEBT 2.

guvenfo'o I W6 1420mm dwzm (9 in mi, attouau s and exact description oi FRIEDRICH BERNHARD FISCHER, OF DRESDEN, GERMANY.

I SCREW-GAGE AND THE LIKE.

Specification of Letters Patent.

Patented F eb.-5, 1907.

Application filed October 16,1903. S lal No. 177.318.

T0 mil Hill/0771 it may concern.-

Be it known that I, FRIEDRICH BERN- HARD FISCHER, a subject of the King 01 Saxony, and a resident of Dresden-A., in the Kingdom of Saxony, Germany, have invented certain new and useful Improvements in Screw-Thread-Testing Devices and I do hereby declare the followin to be a full, clear, the same, reference being had to the accompanying drawings, forming a part of this specification, and to the figures and letters of reference marke thereon.

The object of this invention is to rovide a simple, reliable, and accurate gage or testing the maximum'and minimum diameters of screws, as well as the form of the teeth, by the simple application of the testing device thereto.

, the. base of the thread and the bottom of the spaces' between the teeth and the opposite jaw forming a gage for the greatest maximum diameter of the screw or reatest permissible diameter at the apex of the thread.

The invention further consists in a testing device formed by two bars connected in substantial parallelism with two pairs of parallel gage jaws or faces forming gages one for determining the least permissi sible maximum diameter, the greatest permissible minimum diameter, and the form of the thread.

The invention further consists in certain novel details of construction and combinations and arrangements of arts, all as Wlll be now described, and pointe out particularlyin the appended claims.

Referring to the accompanying drawings, Figure 1 is a side elevation of a testing device embodying the present invention. Fig. 2 1s a plan of the same. Fig. 3 is an end elevale maximumfdiameter and the other having teeth at an angle therein for determining the greatest permis- -tion. Fig. 4 is a side elevation showing both jaws of one pair provided with teeth.

Like letters of reference in the several figures indicate same parts.

The bars a and b, the parallel ends of 'which form the gage-jaws d and e, are spaced and held by intermediate pieces or spacers c and suitable connectin nary'character. .he' proximate faces of the gage-jaws are parallel, and the 'space between them is accurately determined by the s acers but in order that the body portions 0 one or both of the bars may be flexible to a degree such body portion between the spacers is preferably reduced somewhat in thickness. With this construction it is practicable'to finish the bars uniformly, and in setting or assembling the parts one of the s acers may be of.

slightly. less thickness than t e other, and the ends of the bars when seated thereon may still maintain their parallelism, but with the" The proximate faces 0 the aws of the gagescrews'or pins of ordiopening 0 are plain and smooth, andthey are accurately spaced to just prevent. the entry of a screw of the proper maximum diameter, a screw which will enter being less than the permissible maximum diameter.

The faces of the jaws at the gage-opening d, whilethey are of the same general surface formation as those at 0, have in addition teeth formed on a portion thereof conformin to the contour of the spaces in the thread of a screw of proper form and at an angle with relation to the jaws corresponding to the pitch of the screw-thread.

In the construction shown in Figs. 1, 2, 3 one jaw only is provided with teeth, while in Fig. 4 both jaws have teeth thereon. The teeth may, as shown, be formed on a separate or separable angle-piece f for greaterconvenience in manufacture and to enable the toothed portion to be exchanged in case it becomes worn. j

The gage-opening at the end having the teeth is madeofsuch dimensions as to permit the entry of a screw having the proper maximum diameter, proper minimum diameter, and proper form of thread. If the maximum diameter or apex of the thread be too large, entry is prevented by contact with the bottoms of the, spaces between the teeth on the jaw, even though the screw be of proper minimum diameter and the form of the thread correct. If the minimum diameter be too great, the apices of-the teeth will prevent the entry of the screw, even though the maximum diameter be correct. The accuracy in the form of the thread maybe determined in a comparison with the teeth by an examination in end elevation, as shown in Fig. 3, and obviously if the itch of the thread be wrong the screw will not enter properly.

As an exam le of the-use ofthe instrument the screw is st presented squarely to the gage end 0. If it enters, it isat once rejected as smaller than the least permissible .maximum-diameter. if it does not enter, it is then presented squarely to .the gage end d, and if it enters squarely and an examination from end elevation shows the form of the teeth to be correct sit is passed as correct. Any imperfection due either :to 'too great maximum or minimum diameter will-prevent its entry,,and it willbe rejected.

It-willbe'noted thatthe teeth-extend only a limited distanceinfrom'the end ofthe jaw, and thus screwsemay be passedthroughuntil they arevfree from the teeth and withdrawn endwise frombetween the jaws, or the reverse order, may be followed, :thereby facilitating the operation of gaging.

What I claim is a 1.' A screw-testing device havingjtwoparallel bars with testing-jaws at one end, one of which jaws has a series of teeth onits inner face correspondingin form'to the spaces between the thread'of the screw-and extending at an angle corresponding tothepitch of said thread. i

2. A screw+t esting device having two-substantially parallel flat bars .with testing-jaws formed hy-their proximate-faces at opposite ends and spacers rigidly connecting said bars intermediate the testing-jaws.

3. A screw-testing-device having two substantially parallel bars with testing-jaws formed by their roximate faces at opposite ends, one of said ars being reduced in thickness intermediate the ends whereby it is rendered flexible to permit of a reduction in width of one gage-opening between the bars and spacers connectmg the bars intermediate the ends and outside of said flexible portion.

4. A screw-thread-testing device embodying twosubstantially parallel bars, spacers between said bars and beyond which the ends of the bars project in parallelism to form two gage-openings, one of said ends having a series of teeth on its inner face.

5. A screw-thread-testing device embodying two substantially parallel bars, spacers between said bars and beyond which the ends of the bars project in parallelism to form two gage-openings, one of said ends having a series of short teeth on its inner face remote from the spacer whereby a screw may be passed through said teeth and withdrawn endwise from'between the bars.

6. A screwetesting device embodying substantially parallel bars, spacers between said bars and beyondwhich-the ends of thebars project to form-gage-aws and a detachable jaw secured to one 0 said bars and having teeth on its inwardly-facing portion; substantially. asdescribed.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

.FRIEDRICH BERNHARD PlSfHEll.

Witnesses:

OTTO WOLFE, C. J. HUGO BR'L'nvixc. 

